Electric-discharge system



July 24, 1956' K. J. GERMESHAUSEN 2,756,365

ELECTRIC-DISCHARGE SYSTEM Filed Jan. 26, 1955 2 Sheets-Sheet 1 INVENTOR.

KENNETH J. GEWESHALGEN ATTORJVHJ' 2 Sheets-Sheet 2 K. J. GERMESHAUSENELECTRIC-DISCHARGE SYSTEM July 24, 1956 Filed Jan. 26, 1955 IN VEN TOR.

KENNETH J. GERMfiSf/AUSEV ATTORNEYS United States PatentELECTRIC-DISCHARGE SYSTEM Kenneth J. Germeshausen, Newton Centre, Mass.

Application January 26, 1955, Serial No. 484,220

13 Claims. (Cl. 315-234) The present invention relates toelectric-discharge systems, and, though it has application in fields ofmore general usefulness, it is particularly adapted for systems in whicha flash condenser or capacitor is discharged through the gaseous mediumof a gaseous-discharge device for such purposes as the production of asingle flash of light or a repetition of flashes, as in flashphotography, stroboscopic Work and the like.

In my copending application, Serial No. 679,983, filed June 28, 1946,and entitled Electric System, and which matured on November 1, 1955 asUnited States Letters Patent No. 2,722,629, there is' described a newand improved condenser charging-and-discharging apparatus that enablesthe use of relatively small two-electrode fiashtubes in place of largerand more complex three-electrode flashtubes. Through the use of suchtwo-electrode tubes, the flash-producing circuit is simplified, the sizeof the apparatus is reduced, and operation with low-voltage condensersand relatively small power supplies is possible. There are occasions,however, Where it is desired to utilize the advantages of suchlow-voltage condensers and such small-size equipment, but withthree-electrode tubes, and, in particular, with such tubes that candissipate large amounts of energy. The present invention, accordingly,enables the use of three-electrode tubes with the same and even smallerlow-voltage sources, flash condensers and other equipment that operatethe two-electrode tubes, thus retaining the advantages of the circuitsof the said copending application and patent, butsupplemented with thefurther advantages of three-electrode tubes that normally require muchlarger condensers, power supplies and related equipment. i I i i Anobject of the present invention, therefore, is to provide a new andimproved electric'sys tem embodying a three-electrode gaseous dischargedevice that is adapted to operate with low voltages that are ofthemselves far too small normally to operate such three-electrode tubes.

Another object is to provide a new and improved electric system of theabove-described character that, though employing a three-electrodeelectric-discharge: device, is adapted to utilize series triggeringarrangements of the type designed for two-electrode flash devices, asdisclosed in the said copending'application and patent. In summary, thisresult is achieved thr ugh the use of a series triggering arrangementwherein a low voltage source is utilized in combination with a seriesvoltage adding mechanism which is rendered operativesimultaneously withthe application of a triggering impulse to the trigger electrode of athree-electrode tube. A further object of the present invention is toprovide a new and improved electric system embodying a three-electrodedischarge device wherein the triggering electrode discharge is employedto produce a sharply rising high-frequency impulse for simultaneousseries triggering.

Other and further objects will be explained hereinafter and will beparticularly pointed out in the appended claims.

The invention will now be more fully explained in connection with theaccompanying drawings, Fig. 1 of which is a diagrammatic view ofcircuits and apparatus arranged and constructed in accordance with apreferred embodiment of the present invention;

Figs. 2 and 3 are similar views of modifications; and

Fig. 4 is a similar view of still a further modification, particularlyadapted for use with spark-discharge devices.

Referring to Fig. 1, the three-electrode gaseous-discharge tube is shownat 1, provided with a pair of principal electrodes 3 and 5 and a triggeror control electrode 7, which may be either internal or external to thetube 1. The tube, for example, may be of the type described in myLetters Patent No. 2,492,142, issued December 27, 1949, or of the typedisclosed in Letters Patent No. 2,478,901 issued August'lo, 1949 toHarold E. Edgerton, or of any other type, embodying any desired shape,configuration, type of electrodes or gases. A main discharge or flashcondenser or capacitor 11 stores energy by charging from adirect-current source 10, illustrated as a battery, through a currentIimiting-charging impedance 13. A bleeder network 15, His connected inparallel with capacitor 11. The lower electrode of this capacitor 11 isshown connected by conductor 19 to the lower or cathode principalelectrode 5 of the gaseous discharge flash tube 1. The upper electrodeof the capacitor 11 is shown connected in series with a secondaryinductance winding 21 of a preferably saturable transformer 23, to theupper or anode electrode 3 of the gaseous-discharge flashtube 1. Theprimary winding 25 of the transformer 23 is connected on one side by aconductor 27 to the conductor 19, and on the other side to a condenser29. The condenser 29 is connected by a conductor 31 to an intermediateterminal 33 of the bleeder network 15, 17. The condenser 29 is thuscharged in the circuit traceable from the intermediate terminal 33 ofthe bleeder network 15, 17, through the condenser 29, the primarywinding 25, and the conductors 27 and 19, to the lower terminal of thebleeder resistor 17. Also connected by the conductor 31 to theintermediateterminal 33 of the bleeder network 15, 17 is a furthercondenser 35, which is similarly charged through the primary winding 37of a high-voltage trigger transformer 39. The upper terminal of thesecondary winding 41 of the trigger transformer 39 is connected by theconductor 43 to the trigger or control electrode 7 of thethree-electrode gaseous-discharge device 1. The lower terminals of theprimary winding 37 and the secondary winding 41 of the triggertransformer 39 are shown connected together to the conductor 19.

A trigger switch S may be utilized to initiate the triggering of thetube 1. The mechanical trigger switch S may be replaced by an electronictrigge r circuit or any other impulse-producing device, if desired, asdescribed, for example, in the said Letters Patent. Upon the closing ofthe switch S, the condenser 29 and the condenser 35 each becomessubstantially simultaneously discharged. The condenser 29 dischargesthrough the switch Sand the primary winding 25 of the normallyineffective transformer 23, thereby rendering the transformer 23effective to induce a preferably steppedup voltage in the secondarywinding 21 thereof. Simultaneously, the condenser 35 discharges throughthe switch S and the primary winding 37 of the trigger transformer 39inproduce a trigger impulse in the secondary winding that is thus appliedto the trigger electrode 7. i 7' The application of the trigger pulsefrom the secondary winding 41 to the trigger electrode 7 of thegaseousdischarge tube 1 commences partial ionization of the gas in thetube 1. There is simultaneously induced, however, in the secondarywinding 21, a voltage that is added in series with and in the samepolarity'as the voltage stored in the capacitor 11, to produce adischarge between 3 the principal electrodes 3 and 5 of thegaseous-discharge tube 1. Sin'ce'thdtilbl istrig'geredat"th same timethat this voltage in the secondary winding 21 is developed, muchsmaller'voltages are required inthe secondary winding 21'than wouldbethe case if the trigger voltage were not applied to the tube 1. -Thereis a tendency, moreover, as later morefully discussed inconnection withthe embodimentof'Fig. '4," for the energy discharging from the triggerelectrode 7 to increase the principal-electrode voltage differential,thereby to'assist in thefiring of the tube 1. The s'aturable transformer23 may therefore even be of a'much simpler construction and of lesssizeable voltage rating than that required for operation of thetwo-electrode'flashtube's described in the said copending applicationand patent. It-is' easier, therefore, to maintain the secondarywindingll of such a lowenrated transformer 23 at low impedance,thus toprovide for the maximum transfer of energy in the discharge circuitcomprisingthe capacitoflI, the winding 21 and the principal electrodes 3and 5' of the tube 1. The design of the saturablej transformer 23 'istherefore considerably simplified over that required for use with thetwo-electrode tube. The series voltage 'to' beadded to the voltage ofthe capacitor 11' does not, 'indeed, need to. be as large as the voltagerequired in two-electrode fl'ashtube circuits in view of thesimultaneous breaking-down or partial ionization of the tube 1 bytheapplication of the trigger pulse to the trigger electrode 7. Thislower-voltage operation eases up on the rather strict requirements ofthe circuits of the said cop'ending applicationas to the low impedancein the switch S and the inductance of the trigger circuit.

The three-cathode gaseous discharge device 1 may therefore be operatedwith a relatively low-voltage energystorage capacitor 11 through theexpedient of the trigger ing of the three electrode tube 1 with thesimultaneous application of voltage in series with the voltage of thecapacitor 11 by means of the action of the saturable transformer 23. Onemay therefore employ the threeelectrode tube 1 in order to takeadvantage of its ability to handle large amounts of energy in thedischarge, and yet may operate the tube with the same low-voltagecapacitor 11 that could normally beused with only the two-electrodetubes, and with a much lower-voltage saturable transformer 23 than isrequired for two-electrodetube operation.

In the modification of Fig. 2, the condenser 35 and the separate triggertransformer 39 are not employed. The condenser 29, however, is utilizednot only to energize the triggering of the trigger electrode'7 of thegaseousdischarge device 1, but also toproduce the series voltage that isto be added to the capacitor 11 in the discharge circuit. Thus, when theswitch S is closed, the condenser 29 discharges through the primarywinding 25 of the somewhat modified saturable transforr'ner23. Upon thecore of this transformer. 23 may be wound a further high-voltagehigh-impedancesecondary winding 26 cooperating with the transformer 23and which serves the function of the trigger transformer 39 in thesystem of Fig. 1 and is connected between the condenser 29 and thetrigger electrode 7. When the switch S is closed, therefore, thecondenser 29 discharges through the primary winding 25, rendering thetransformer 23 effective to induce simultaneously series voltage in thesecondary winding 21 to add to the voltage of the capacitor 11 be tweenthe principal electrodes .and 5, and a trigger voltage impulse in thefurther secondary winding 26 to trigger the trigger electrode 7..v

While the transformer 23 is shown in Figs. 1 and 2 in series connectionbetween theupper electrode of the flash capacitor 11 and the anode 3 ofthe gaseous-discharge tube 1, it could equally well be placed in theconnection to the cathode principal electrode 5. In Fig.3, therefore,for purposes of illustration, the secondary winding 21 of thetransformer 23-of the circuit of Fig. 2 is shown con.- nected betweenthe lower electrode of the capacitor'll' and the cathode principalelectrode 5 of the flashtube 1. The invention is by no" meansrestricted, however, to the gaseous electric-discharge tubes of thecharacter before described. Other electric-discharge devices maysimilarly be employed such as, for example, spark gaps of the typedisclosed in Letters Patent No. 2,478,906, issued on the said August 1d,1949 to the said Harold E. Edgerton.

In Fig. -4,--a-c-ircuit particularly adaptedfor use with spark gaps isillustrated, though this circuit is also useful with flask tubes. 'Wherea spark gap is employed instead of a gaseous-discharge tube, it isnecessary to the attainment of high etficiency that the gas pressure berelatively high; say, in excessof about 1. atmosphere. Even with suchhigh pressure, however, and even though small gap spacings of the orderof from about three-eighths to about one-half of an inch are employed,spark gaps have been found not tooperate consistently at low voltages.It is usually necessary, therefore, to applyivoltages in excess of aboutfifteen hundred "volts to obtain satisfactory spark-gap operation.Through the techniques of the present invention, however, 'l'ow voltagesmay be utilized reliably to operatesparkg'aps. i

The principal electrode 3 of the spark gap 1'-is shown connected throughthe secondary winding 45 of a sat urable transformer. 47 to the upperelectrode of the capacitor 11. The lower electrode of the capacitor 11is connected by a conductor 51 through the primary winding 49 of thesaturabletransformer 47,and by a conductor 53 to the cathode principalelectrode 5 of the spark gap 1'. The trigger electrode-7' is connectedby conductor 43 to the upper terminal of the secondary trigger winding41 of the trigger tra'nsformer 39. The lower terminal of the secondary.winding 41is connected to the conductor 19. Thewindings 45 and 49 may,if'desired, be separate inductors. I

Upon the application of the trigger impulse to the primary. Winding 37of the trigger transformer 39, efiected by the closing of the switch S,a high-voltage trigger impulse is developed across the secondary winding41. The high voltage developed across the secondary winding 41 applies abreakdown potential between, say, thetrigger electrode 7 and the lowerprincipal electrode'5; The resulting short-circuit between theelectrodes 7' and 5' results in the application of the high triggervoltage to the primary winding 49 of" the saturable transformer 47 inthe circuit traceable from the upper terminal of the winding 41, byconductor 43 to the trigger electrode 7' and the cathode 5, thence byconductor 53 throughthe primary Winding 49, and by conductor 51 to thelower terminal of the secondary winding 41.

There is a limited time in which one can apply such 7 a high voltage toa saturable transformer. winding before the transformer saturatesx'lf,for example,.a 5000- volt impulse is to be applied to the winding '49from the trigger-transformer 39, andthe saturable transformer 47saturates in one microsecond, then the. voltage must be fully applied tothe transformer 47 in substantially one microsecond. The circuit ofFig.4 effects this automatically, since the distributed capacitance 55 ofthe trigger transformer secondarywinding 41 tends to maintain the highvoltage developed in the secondary winding 41. There is thus almostinstantaneously applied to the primary winding 49 of the jsaturabletransformer 47 the high frequency impulse from the trigger transformersecondary winding 41, as before described. The result is that theprincipal electrode. 5' assumes .the potential of the voltage developedin the trigger transformer secondary winding.41, thereby lowering thevoltage of the principal electrode -5 with respect to the other anodeprincipal electrode 3' of the spark gapl' by at least an amount equal tothe voltage developed across thesecondary Winding 41'. If, for example,the voltage in the triggentransformer scondarywinding 41 is 5000 volts,then the electrode 5 instantaneously'becomes 5000 volts negative withrespect to the electrode 3. The secondary winding 45 of the saturabletransformer 47, however, is so Wound that the voltage induced in it addsin the same sense with the relatively low voltage of the condenser 11.The principal electrodes 3' and 5' thus differ in potential not only bythe high voltage developed across the trigger transformer secondarywinding 41, but, also, by the additional voltage of the capacitor 11 andthe voltage developed in the secondary Winding 45 of the saturabletransformer 47 as it is rendered effective to add voltage in series withthe voltage of the capacitor 11. a A very large voltage diflerentialbetween the electrodes 3 and 5' is thus instantaneously built up,causing the spark gap to flash over and to discharge the voltage of thecapacitor 11 and the voltage in the secondary winding 45 through thespark gap 1".

Through the expedient of similar saturable windings 49 and 45, it makesno difference in the operation of the circuit whether the triggerelectrode 7 initially arcs over to the principal electrode 3' or to theprincipal electrode 5' to start the above-described sequence. In bothcases, the trigger impulse applied to the secondary winding 41 is almostsimultaneously applied to the saturable transformer 47, producing alarge over-voltage between the electrodes 3' and 5' in order to permitthe discharge therebetween. This is reliably accomplished, moreover,even though a voltage is employed on the capacitor 11 that is relativelylow, say of the order of 450 or 500 volts. A further feature of thecircuit of Fig. 4 resides in the fact that it is inherently adapted forthe use of low currents in the trigger circuit of the primary winding 37of the trigger transformer 39.

Further modifications will occur t o those skilled in the art and allsuch are considered to fall within the spirit and scope of the inventionas defined in the appended claims. I,

What is claimed is:

1. An electric flash-producing system having, in combination, anelectric flash device having a pair of principal electrodes and atrigger electrode, energy storage means, a charging circuit for storingvoltage in the energy storage means, a discharge circuit for the energystorage means connected to the principal electrodes and includingnormally ineffective means for adding voltage, when effective, in thedischarge circuit in series with and in the same polarity as the voltageof the energy storage means, and means for supplying a trigger impulseto the trigger electrode and substantially simultaneously rendering thenormally ineffective means effective, thereby to enable the energystorage means to discharge through the discharge circuit in order toproduce a flash between the principal electrodes of the flash device.

2. An electric flash-producing system having, in combination, anelectric flash device having a pair of principal electrodes and atrigger electrode, a condenser, means for charging the condenser, adischarge circuit for the condenser connected to the principalelectrodes and including an inductor for adding voltage, when voltage isinduced therein, in the discharge circuit in series with and in the samepolarity as the voltage of the condenser, and means for supplying atrigger impulse to the trigger electrode and substantiallysimultaneously inducing a voltage in the inductor, thereby to enable thecondenser to discharge through the discharge circuit in order to producea flash between the principal electrodes of the flash device.

3. An electric flash-producing system having, in combination, anelectric flash device having a pair of principal electrodes and atrigger electrode, a condenser, means for charging the condenser, adischarge circuit for the condenser connected to the principalelectrodes and including a saturable-core inductor for adding voltage,

when voltage is induced therein, in the discharge circuit in series withand in the same polarity as the voltage of the condenser, and means forsupplying a trigger impulse to the trigger electrode and substantiallysimultaneously inducing a voltage in the inductor, thereby to enable thecondenser to discharge through the discharge circuit'in order to producea flash between the principal electrodes of the flash device.

4. An electric flash-producing system having, in combination, anelectric flash device having a pair of principal electrodes and atrigger electrode, a condenser, means for charging the condenser, atransformer having a primary winding and a secondary winding, adischarge circuit for the condenser connected to the principalelectrodes and including the secondary winding disposed to add voltagein the discharge circuit in series with and in the same polarity as thevoltage of the condenser, and means for supplying a trigger impulse tothe trigger electrode and substantially simultaneously an impulse to theprimary winding, thereby to enable the condenser to discharge throughthe discharge circuit in order to produce a flash between the principalelectrodes of the flash device.

5. An electric flash-producing system having, in com bination, anelectric flash device having a pair of principal electrodes and atrigger electrode, a condenser, means for charging the condenser, atransformer having a primary winding, a saturable core and a secondarywinding, a discharge circuit for the condenser connected to theprincipal electrodes and including the secondary winding disposed to addvoltage in the discharge circuit in series with and'in the same polarityas thevoltag'e of the condenser, and means forsupplying atrigger impulseto the trigger electrode and substantially simultaneously an impulse tothe primary winding, thereby to enable the condenser to dischargethrough the discharge circuit in order to produce a flash between theprincipal electrodes of the flash device.

6. An electric flash-producing system having, in combination, anelectric flash device having a pair of principal electrodes and atrigger electrode, condenser means, means for charging the condensermeans, a discharge circuit for the condenser means connected to theprincipal electrodes and including normally ineffective means for addingvoltage, when effective, in the discharge circuit in series with and inthe same polarity as the voltage of the condenser means, a bleedernetwork connected with the condenser-charging means, further condensermeans, means for charging the further condenser means from the bleedernetwork, means for discharging the further condenser means, and meanscontrolled by the last-named means for supplying a trigger impulse tothe trigger electrode and substantially simultaneously rendering thenormally ineffective means effective, thereby to enable the first-namedcondenser means to discharge through the discharge circuit thereof inorder to produce a flash between the principal electrodes of the flashdevice.

7. An electric flash-producing system having, in combination, anelectric flash device having a pair of principal electrodes and atrigger electrode, a trigger winding connected to the trigger electrode,condenser means, means for charging the condenser means, a transformerhaving a primary Winding, a saturable core and a secondary winding, adischarge circuit for the condenser means connected to the principalelectrodes and including the secondary winding disposed to add voltagein the discharge circuit in series with and in the same polarity as thevoltage of the condenser means, a bleeder network connected with thecondenser-charging means, further condenser means, means for chargingthe further condenser means from the bleeder network, means fordischarging the further condenser means, and means controlled by thelast-named means for supplying an impulse to the trigger winding andsubstantially simultaneously an impulse to the primary winding to enable7 the first-named" condenser means to discharge through the dischargecircuit thereof in order to produce a flash between the principalelectrodes of the flash device. 7

8. An electric flash-producing system as claimed in claim 7 and in whichthe further condenser means comprises two condensers, one connected todischarge through the said primary winding and the other to dischargethrough a further primary winding cooperative with the said triggerwindin g. Y

9. An electric flash-producing system as claimed in claim- 7 and inwhich the said trigger winding cooperates with the transformer windings;

a 10. An electric system having, in combination, a gaseous-dischargedevice having a pair of principal electrodes and a trigger electrode,energy storage means, a charging circuit for storingvoltage in theenergy storage means, a discharge circuit for the energy storagemeansconnected to the principal electrodes and including normally inefiectivemeans for adding voltage, when eflective, in the discharge circuit inseries with and in the same polarity as the voltage of the energystorage means, and means for supplying a trigger impulse to the triggerelectrode and substantially simultaneously rendering the normallyinefiiective means effective, thereby to enable the energy storage meansto discharge through the discharge circuit in order-to produce adischarge between the principal electrodes of the gaseous-dischargedevice.

11. Anelectric system having, in combination, a sparkgap device having apair of principal electrodes and a trigger electrode, energy storagemeans, a charging circuit for storing voltage in the energy storagemeans, a discharge circuit for the energy storage means connected to theprincipal electrodes and including normally inefiective means for addingvoltage, when effective, in the discharge circuit in series with and inthe same polarity as the voltage of the energy storage means, and meansfor supplying a trigger impulse to the trigger electrode andsubstantially simultaneously rendering the normally inefiectivemeanseffective, thereby to enable the energy storage means to-dischargethrough the discharge circuit in order to produce a discharge betweenthe principal electrodes of the spark-gap device.

t 12. An electric system having, in combination, an electric-dischargedevice having a pair of principal electrodes and a trigger electrode, atriggertransformer the secondary winding of which is connected betweenthe trigger electrode and oneof the principal electrodes, a condensermeans for charging the condenser,.a discharge circuit for the condenserconnected to the principal electrodes and including a saturable-coretransformer the windings of which arerconnectedrin series with thecondenser, and means for supplying a trigger impulse to the triggertransformer to break down the electric-discharge device between thetrigger electrode and one of the principal electrodes and substantiallysimultaneously to apply an impulse to the saturable-core transformer,thereby to enable the condenser to discharge through the dischargecircuitrto produce a discharge between the principal electrodes of theflash device.

13. An electric system having, in combination, an electric-dischargedevice having a pair of principal electrodes and a trigger electrode, atrigger transformer the secondary' winding of which is connected betweenthe trigger electrode and one of the principal electrodes, a condenser,means for charging the condenser, a discharge circuit for the condenserconnected to the principal electrodes and including a saturable-coreinductor connected in series with the condenser, and means for supplyinga trigger impulse to the trigger transformer-to break down theelectric-discharge device between the trigger electrode and one of theprincipal electrodes and substantially simultaneously to apply animpulse to the saturable-core inductor, thereby to enable the condenserto discharge between the principal electrodes of the flash device.

No references cited.

